Re: CGMINER miner overclock monitor fanspeed RPC in C linux/windows/osx 2.1.0
That's the spirit 
That made me giggle
Well, my point is, it doesn't have a reason - one restart it's faster, the other - slower, doesn't seem to have any pattern at all, since I've had the same behaviour through different driver and miner versions. Otherwise there were no software or hardware changes.
It couldn't be that PP thingy (http://en.wikipedia.org/wiki/ATI_PowerPlay) that changes card clocks and all whenever it feels like it?